Silane/urea compound as a heat-activatable curing agent for epoxide resin compositions

ABSTRACT

Silanes of formula (I), or of substrates whose surface is coated or derivatized with a silane of formula (I), as a curing agent for epoxy resins which is activatable at elevated temperature. Such thermosetting epoxy resin compositions allow a large reduction in the curing temperature without great impairment of their storage stability.

TECHNICAL FIELD

The invention relates to the field of silanes and curing agents forthermosetting epoxy resins.

PRIOR ART

Silanes have been known for quite some time as bonding agents foradhesives.

Urea silanes are used for producing sol gels and xerogels, as disclosedin Russ. J. Appl. Chem. 2006, 79, 981-986 and Russ. J. Gen. Chem. 2004,74, 1658-1664. The urea silanes are condensed with tetraethoxysilane toproduce a uniform sol or gel.

Thermosetting epoxy resin compositions have been known for quite sometime. For this purpose curing agents are used which are activated atelevated temperature. Urea compounds are an important class of suchheat-activatable curing agents for epoxy resins. Such urea compoundsoften have an accelerating effect on other heat-activatable curingagents containing epoxy resins.

One important application of thermosetting epoxy resin compositions isfound in vehicle manufacture, in particular for adhesive bonding or forfoaming of cavities in body shells. In both cases, after application ofthe epoxy resin composition the body is heated in a cathodic dip coating(CDC) oven, thereby also curing and optionally foaming the thermosettingepoxy resin composition. For example, WO 2004/106402 A2 and WO2004/055092 A1 disclose thermosetting epoxy resin compositionscontaining urea compounds as heat-activatable curing agents.

However, efforts are currently underway in the industry to greatlyreduce the curing temperature. Thus, there is a great need in theindustry for thermosetting epoxy resin compositions which also cure atlower temperatures, i.e., at temperatures less than 180° C., after avery short time, typically 10 to 15 minutes. For this reason, aromaticureas are used which are significantly more reactive due to theirstructure. However, it has been shown that using such aromatic ureasresults in considerable problems in the storage stability of thethermosetting epoxy resin compositions.

Description of the Invention

The object of the present invention, therefore, is to provideheat-activatable curing agents for epoxy resins, which allow curing ofepoxy resins at lower temperatures and still ensure good storagestability of the epoxy resin composition containing theseheat-activatable curing agents.

This object has surprisingly been achieved by using a silane of formula(I) according to Claim 1.

Such silanes are extremely well suited as heat-activatable curing agentsfor epoxy resin compositions. In addition, they may be satisfactorilyused for the coating or derivatization of substrates, in particularfillers or flat substrates, which may then be used as heat-activatablecuring agents.

The silanes of formula (I), in particular formula (I a), arecharacterized in that, as a component of thermosetting epoxy resincompositions, they allow a large reduction in the curing temperaturewithout great impairment of their storage stability. They are thereforevery well suited for single-component thermosetting epoxy adhesives,which in particular contain impact modifiers, as body shell adhesivesfor vehicle manufacture. It has been shown to be particularlyadvantageous to use the silanes of formula (I) with furtherheat-activatable curing agents.

It has also been shown that the silanes of formula (I) result inincreased adhesion to various subsurfaces.

Further aspects of the invention are the subject matter of the furtherindependent claims. Particularly preferred embodiments of the inventionare the subject matter of the dependent claims.

Approaches for Carrying Out the Invention

In a first aspect, the present invention relates to the use of a silaneof formula (I), or of a substrate whose surface is coated or derivatizedwith a silane of formula (I), as a curing agent for epoxy resins whichis activatable at elevated temperature.

In this regard, A stands for an optionally branched alkylene groupcontaining 1 to 4 C atoms, or for a phenylene group.

Z¹ stands for H or an alkyl group containing 1 to 4 C atoms, inparticular a methyl or ethyl group.

Z² stands for H or a phenyl group, or an alkyl group containing 1 to 8 Catoms, in particular a methyl group.

Z³ stands for H or a monofunctional aromatic or cycloaliphatic oraliphatic group containing 1 to 8 C atoms, which optionally contains atleast one carboxylate, nitrile, nitro, phosphonate, or sulfonic orsulfonate group, or stands for A-Si(Z²)_(3-a)(OZ¹)_(a).

Z⁴ stands for H or a monofunctional aromatic or cycloaliphatic oraliphatic group containing 1 to 8 C atoms.

Z⁵ stands for a b-functional aromatic or araliphatic or cycloaliphaticor aliphatic group containing 1 to 40 C atoms, or for the groupA-Si(Z²)_(3-a)(OZ¹)_(a).

In addition, X stands for O or S, a stands for 1 or 2 or 3, and b standsfor 1 or 2 or 3 or 4.

Lastly, the condition applies that either Z³ or Z⁴ stands for H.

Thus, of the two groups Z³ and Z⁴ attached to the urea group (NCON) orthiourea group (NCSN), one, but not both, stands for H.

Namely, it is important for the invention that the urea group(s) orthiourea group(s) present in formula (I) is/are neither disubstitutednor tetrasubstituted, but, rather, is/are trisubstituted urea group(s)or thiourea group(s).

In the present document, use of the terms “independently” in conjunctionwith substituents, radicals, or groups is to be construed to mean thatin the same molecule substituents, radicals, or groups which are denotedhaving the same meaning may at the same time be present with a differentmeaning.

In the entire present document, the prefixes “poly,” for example in“polyisocyanate,” “polythioisocyanate,” “polyamine,” “polyol,”“polyphenol,” and “polymercaptan,” refer to molecules which formallycontain two or more of the particular functional groups.

In the present document, an “impact modifier” is understood to mean anadditive to an epoxy resin matrix which even at low addition quantities,in particular 0.1-50% by weight, preferably 0.5-40% by weight, resultsin a distinct increase in the toughness and which is therefore able toabsorb fairly high impact or shock stress before the matrix ruptures orbreaks.

The dashed lines in the formulas in the present document in each caserepresent the bond between the particular substituent and the associatedmolecular moiety.

In the present document, the term “polymer” includes on the one hand acollective of macromolecules produced by a polyreaction (polymerization,polyaddition, polycondensation) which are chemically uniform butdifferent with regard to polymerization rate, molar mass, and chainlength. On the other hand, the term also includes derivatives of such acollective of macromolecules from polyreactions, i.e., compoundsobtained from reactions such as additions or substitutions, for example,of functional groups on specified macromolecules, and which may bechemically uniform or chemically nonuniform. The term further includesso-called “prepolymers,” i.e., reactive oligomeric prepolymers, whosefunctional groups take part in the synthesis of macromolecules.

The term “polyurethane polymer” includes all polymers which are producedaccording to the so-called diisocyanate polyaddition process. This termalso includes polymers which are practically or completely free ofurethane groups. Examples of polyurethane polymers are polyetherpolyurethanes, polyester polyurethanes, polyether polyureas, polyureas,polyester polyureas, polyisocyanurates, and polycarbodiimides.

It is preferred that a stands for 2 or 3. Most preferably, a representsa value of 3.

The group A preferably represents an optionally branched alkylene groupcontaining 1 to 4 C atoms. In particular, A stands for a methylene,propylene, n-butylene, or isobutylene group. A particularly preferablystands for a propylene group.

It is preferred that b stands for 1 or 2.

The methyl group is the preferred group for Z³ or Z⁴ or Z⁵ as amonofunctional aliphatic group containing 1 to 8 C atoms.

It has been shown to be particularly advantageous when the silane offormula (I) contains no aromatic substituents.

If Z³ stands for a monofunctional aromatic or cycloaliphatic oraliphatic group containing 1 to 8 C atoms, and which contains at leastone carboxylate, nitrile, nitro, phosphonate, or sulfonic or sulfonategroup, Z³ in particular stands for the group of formula (III)

where

-   Z⁵ and Z⁶ independently stand for a hydrogen atom or for a radical    selected from the group comprising —Z⁹, —OOOZ⁹, and —CN, and-   Z⁷ stands for a hydrogen atom or for a radical selected from the    group comprising —CH₂—COOZ⁹, —COOZ⁹, —CONHZ⁹, —CON(Z⁹)₂, —CN, —NO₂,    —PO(OZ⁹)₂, —SO₂Z⁹, and —SO₂OZ₉,    where-   Z⁹ stands for a monofunctional hydrocarbon radical in particular    containing 1 to 6 C atoms, and optionally containing at least one    heteroatom.

The silanes of formula (I) may be easily synthesized in various ways.

In a first variant, an isocyanate or thioisocyanate of formula (II a) isreacted with a secondary aminosilane of formula (II b), i.e., in thiscase Z³ being different from H, to produce the silane of formula (I).

In a second variant, a secondary amine of formula (II c), i.e., in thiscase Z⁴ being different from H, is reacted with an isocyanatosilane orthioisocyanatosilane of formula (II d) to produce the silane of formula(I).

In a third variant, a compound of formula (II e) is reacted with anaminosilane of formula (II f) to produce the silane of formula (I).

The first variant is suited in particular for producing silanes havingmultiple urea groups or thiourea groups, i.e., where b>1. Thepolyisocyanates necessary for this purpose are easily obtainable.

Mono- or polyisocyanates are suited as isocyanates of formula (II a).The mono- or polyisocyanates may be aromatic or aliphatic.

Examples of suitable aromatic polyisocyanates are monomeric di- ortriisocyanates such as 2,4- and 2,6-toluylene diisocyanate and any givenmixtures of these isomers (TDI), 4,4′-, 2,4′-, and 2,2′-diphenylmethanediisocyanate and any given mixtures of these isomers (MDI), mixtures ofMDI and MDI homologs (polymeric MDI or PMDI), 1,3- and 1,4-phenylenediisocyanate, 2,3,5,6-tetramethyl-1,4-diisocyanatobenzene,naphthalene-1,5-diisocyanate (NDI),3,3′-dimethyl-4,4′-diisocyanatodiphenyl (TODI), dianisidine diisocyanate(DADI), 1,3,5-tris-(isocyanatomethyl)benzene,tris-(4-isocyanatophenyl)methane,tris-(4-isocyanatophenyl)thiophosphate, oligomers and polymers of theabove-mentioned isocyanates, and any given mixtures of theabove-mentioned isocyanates. MDI and TDI are preferred.

Examples of suitable aliphatic polyisocyanates are monomeric di- ortriisocyanates such as 1,4-tetramethylene diisocyanate,2-methylpentamethylene-1,5-diisocyanate, 1,6-hexamethylene diisocyanate(HDI), 2,2,4- and 2,4,4-trimethyl-1,6-hexamethylene diisocyanate (TMDI),1,10-decamethylene diisocyanate, 1,12-dodecamethylene diisocyanate,lysine diisocyanate and lysine ester diisocyanate, cyclohexane-1,3- and-1,4-diisocyanate, 1-methyl-2,4- and -2,6-diisocyanatocyclohexane, andany given mixtures of these isomers (HTDI or H₆TDI),1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (=isophoronediisocyanate or IPDI), perhydro-2,4′- and -4,4′-diphenylmethanediisocyanate (HMDI or H₁₂MDI),1,4-diisocyanato-2,2,6-trimethylcyclohexane (TMCDI), 1,3- and1,4-bis-(isocyanatomethyl)cyclohexane, m- and p-xylylene diisocyanate(m- and p-XDI), m- and p-tetramethyl-1,3- and -1,4-xylylene diisocyanate(m- and p-TMXDI), bis-(1-isocyanato-1-methylethyl)naphthalene, dimericand trimeric fatty acid isocyanates such as3,6-bis-(9-isocyanatononyl)-4,5-di-(1-heptenyl)cyclohexene (dimeryldiisocyanate), α,α,α′,α′,α″,α″-hexamethyl-1,3,5-mesitylenetriisocyanate, oligomers and polymers of the above-mentionedisocyanates, and any given mixtures of the above-mentioned Isocyanates.HDI and IPDI are preferred.

In another embodiment, a polyisocyanate in the form of a monomeric di-or triisocyanate or an oligomer of a monomeric diisocyanate is suitableas polyisocyanate, the above-mentioned aromatic and aliphatic di- andtriisocyanates, for example, being suitable as monomeric di- ortriisocyanate. The oligomers of HDI, IPDI, and TDI are particularlysuited as oligomers of a monomeric diisocyanate. In practice, sucholigomers usually represent mixtures of substances having differentoligomerization rates and/or chemical structures. The oligomerspreferably have an average NCO functionality of 2.1 to 4.0, and containin particular isocyanurate, iminooxadiazindione, uretdione, urethane,biuret, allophanate, carbodiimide, uretonimine, or oxadiazintrionegroups. The oligomers preferably have a low content of monomericdiisocyanates. Commercially available types are in particular HDIbiurets, for example DESMODUR N 100 and DESMODUR N 3200 (from Bayer),TOLONATE HDB and TOLONATE HDB-LV (from Rhodia), and DURANATE 24A-100(from Asahi Kasei); HDI isocyanurates, for example DESMODUR N 3300,DESMODUR N 3600, and DESMODUR N 3790 BA (from Bayer), TOLONATE HDT,TOLONATE HDT-LV, and TOLONATE HDT-LV2 (from Rhodia), DURANATE TPA-100and DURANATE THA-100 (from Asahi Kasei), and CORONATE HX (from NipponPolyurethane); HDI uretdiones, for example DESMODUR N 3400 (from Bayer);HDI iminooxadiazindiones, for example DESMODUR XP 2410 (from Bayer); HDIallophanates, for example DESMODUR VP LS 2102 (from Bayer); IPDIisocyanurates, for example DESMODUR Z 4470 (from Bayer) and VESTANATT1890/100 (from Evonik); TDI oligomers, for example DESMODUR IL (fromBayer); and mixed isocyanurates based on TDI/HDI, for example DESMODURHL (from Bayer).

Particularly suited as monoisocyanates are butyl isocyanate, pentylisocyanate, hexyl isocyanate, octyl isocyanate, decyl isocyanate,dodecyl isocyanate, octadecyl isocyanate, cyclohexyl isocyanate,methylcyclohexyl isocyanate, phenyl isocyanate, benzyl isocyanate,2-methoxyphenyl isocyanate, or p-toluenesulfonyl isocyanate.

Mono- or polythioisocyanates are suitable as thioisocyanates of formula(II a). The mono- or polythioisocyanates may be aromatic or aliphatic.

Particularly suited as thioisocyanates are the compounds which areanalogous to the above-mentioned mono- or polyisocyanates, and whichcontain thioisocyanate group(s) instead of isocyanate group(s).

The secondary aminosilanes of formula (II b) are sometimes commerciallyavailable, or may be prepared from an aminosilane of formula (II f), inparticular by a Michael-type addition to a Michael acceptor of formula(III a) or (III b).

In the present document, the term “Michael acceptor” refers to compoundswhich, due to their double bonds which are activated by electronacceptor radicals, are able to take part in a nucleophilic additionreaction with primary amino groups (NH₂ groups) in a manner analogous tothe Michael addition (hetero-Michael addition).

Particularly preferred Michael acceptors of formula (III a) or (III b)are acrylonitrile, acrylates and methacrylates, acrylamides ormethacrylamides, diesters of maleic acid and fumaric acid, citraconicacid diester, and itaconic acid diester.

Preferred secondary aminosilanes of formula (II b) which are thusobtained via a Michael-type addition areN-(3-trimethoxysilylpropyl)aminosuccinic acid dimethyl ester and diethylester, and the analogs thereof with ethoxy or isopropoxy groups insteadof methoxy groups on the silicon atom, most preferablyN-(3-trimethoxysilylpropyl)aminosuccinic acid diethyl ester.

Also particularly suited as secondary aminosilanes of formula (II b) areN-butyl-3-aminopropyltrimethoxysilane,N-phenyl-3-aminopropyltrimethoxysilane,N-butyl-3-aminopropyltriethoxysilane, andN-phenyl-3-aminopropyltriethoxysilane.

In one embodiment, a secondary aminosilane of formula (II b) in which Z³stands for A-Si(Z²)_(3-a)(OZ¹)_(a) is used. Such secondary aminosilanesare preferably bis(3-trimethoxysilylpropyl)amine orbis(3-triethoxysilylpropyl)amine.

Particularly suited as secondary amine of formula (II c) aredimethylamine, diethylamine, di-n-propylamine, diisopropylamine,di-n-butylamine, diisobutylamine, di-sec-butylamine, dipentylamine,dihexylamine, di-2-ethylhexylamine, cyclohexylamine, cycloheptylamine,N-methylethylamine, N-methylbutylamine, N-ethylbutylamine,dicyclohexylamine, diphenylamine, and dibenzylamine.

Particularly suited as isocyanatosilane or thioisocyanatosilane offormula (II d) are those selected from the group comprisingisocyanatomethyltrimethoxysilane, isocyanatomethyldimethoxymethylsilane,3-isocyanatopropyltrimethoxysilane,3-isocyanatopropyldimethoxymethylsilane,thioisocyanatomethyltrimethoxysilane,thioisocyanatomethyldimethoxymethylsilane,3-thioisocyanatopropyltrimethoxysilane,3-thioisocyanatopropyldimethoxymethylsilane, and the analogs thereofwith ethoxy or isopropoxy groups instead of methoxy groups on thesilicon atom. 3-Isocyanatopropyltrimethoxysilane and3-thioisocyanatopropyltrimethoxysilane, in particular3-isocyanatopropyltrimethoxysilane, are preferred as isocyanatosilane orthioisocyanatosilane of formula (II d).

The compounds of formula (II e) are easily obtainable or commerciallyavailable. N,N-Dimethylcarbamoyl chloride is particularly preferred as acompound of formula (II e).

Particularly suited as aminosilane of formula (II f) are aminosilanesselected from the group comprising 3-aminopropyltrimethoxysilane,3-aminopropyldimethoxymethylsilane,3-amino-2-methylpropyltrimethoxysilane, 4-aminobutyltrimethoxysilane,4-aminobutyldimethoxymethylsilane,4-amino-3-methylbutyltrimethoxysilane,4-amino-3,3-dimethylbutyltrimethoxysilane,4-amino-3,3-dimethylbutyldimethoxymethylsilane,2-aminoethyltrimethoxysilane, 2-aminoethyldimethoxymethylsilane,aminomethyltrimethoxysilane, aminomethyldimethoxymethylsilane,aminomethylmethoxydimethylsilane, and the analogs thereof with ethoxy orisopropoxy groups instead of methoxy groups on the silicon atom. Theaminosilane of formula (II f) is particularly preferably3-aminopropyltrimethoxysilane, 3-aminopropyldimethoxymethylsilane,3-aminopropyltriethoxysilane, or 3-aminopropyldiethoxymethylsilane.

Thus, for example, suitable silanes of formula (I) may be prepared asaddition products of 3-aminopropyltrimethoxysilane withN,N-dimethylcarbamoyl chloride, of N-methyl-3-aminopropyltriethoxysilanewith butyl isocyanate or HDI or IPDI, ofN-cyclohexyl-3-aminopropyltrimethoxysilane with phenyl isocyanate orbutyl isocyanate or HDI or MDI, of 3-isocyanatopropyltriethoxysilanewith dimethylamine, of N-phenyl-3-aminopropyltriethoxysilane with butylisocyanate or phenyl isocyanate, ofN-phenyl-3-aminopropyltriethoxysilane with HDI or MDI, ofbis(3-trimethoxysilylpropyl)amine with butyl isocyanate or phenylisocyanate or HDI or MDI, of 3-aminopropylmethyldimethoxysilane withN,N-dimethylcarbamoyl chloride, or N-methyl-3-aminopropyldimethoxysilanewith butyl isocyanate, phenyl isocyanate, HDI, or MDI.

On the one hand, particularly preferred are silanes of formula (I) inwhich b is different from 1 and Z⁴ stands for H.

Specific silanes of formula (I), namely, silanes of formula (I a), arealso the subject matter of the present invention.

Silanes of formula (I a) may be divided into three classes:

The silanes are members of either a first class (class 1), a secondclass (class 2), or a third class (class 3).

In the class 1 silanes of formula (I a),

-   -   A is CH₂—CH₂—CH₂, Z′ is CH₃, Z³ is H, Z⁴ is CH₃, Z⁵ is CH₃, X is        O, and b is 1.

In class 2 silanes of formula (I a),

-   -   A is CH₂—CH₂—CH₂, Z¹ is CH₃, Z³ is CH₃, Z⁴ is H, Z⁵ is CH₃, X is        O, and b is 1.

In class 3 silanes of formula (I a),

-   -   A is CH₂, Z¹ is CH₃ or CH₂CH₃, Z³ is H, Z⁴ is a monofunctional        aliphatic group containing 1 to 12 C atoms, Z⁵ is a        monofunctional aliphatic group containing 1 to 12 C atoms, X is        O, and b is 1.

For the sake of completeness, it is noted at this point that, due to thefact that these silanes of formula (I a) are selected silanes of formula(I), it is understood as a matter of course that statements made in thepresent document regarding silanes of formula (I) also apply for silanesof formula (I a), even if in the particular case direct reference is notmade to formula (I a).

The silane of formula (I) may be used directly as a curing agent forepoxy resins which is activatable at elevated temperature, or the silaneof formula (I) may be present on the surface of a substrate and used asa curing agent for epoxy resins which is activatable at elevatedtemperature. The surface of the substrate may be coated with the silaneof formula (I), or may be derivatized, i.e., chemically bound, withsame. The type of substrate primarily determines whether a coating or aderivatization of a surface of a substrate is possible using the silaneof formula (I).

Thus, a substrate whose surface is coated or derivatized with silane offormula (I) is also the subject matter of the present invention.

Silane groups, such as those present in the silane of formula (I), haveat least one Si—O—Z¹ functionality, and under the influence of waterhydrolyze to form silanol groups (—Si—OH). Such silanol groups are thenable to condense with surface groups, in particular surface OH groups,resulting in chemical binding of the silane of formula (I) to thesurface of the substrate (=derivatization of the surface of thesubstrate with the silane of formula (I)). It is of course clear to oneskilled in the art that silanol groups may also condense with oneanother, possibly forming siloxanes. Depending on the substrate,however, the silane may also be present unchanged at the surface of thesubstrate.

By using a silane of formula (I) which is bound to or present on asurface, this silane is continuously, or at least temporarily,immobilized on the substrate surface. Such immobilization has theadvantage that the curing agent may be used selectively at certainlocations.

Fillers on the one hand and flat substrates on the other hand areprimarily used as such a substrate,

In one preferred embodiment the substrate is a flat substrate. Such flatsubstrates are in particular those which are to be adhesively bonded.For example, such flat substrates are planar substrates such as sheets,disks, or flanges; or arched substrates such as fenders, headlighthousings, pipes, or cavities.

One particularly suitable application of such coated or derivatized flatsubstrates is the following method for adhesive bonding, comprising thefollowing steps:

-   α) Applying a silane of formula (I) to the surface of a flat    substrate to be adhesively bonded;-   β) Applying an epoxy resin composition containing at least one epoxy    resin EH, having on average more than one epoxide group per    molecule, to the surface which is coated or derivatized with silane    of formula (I);-   γ) Contacting the epoxy resin composition with another surface of a    substrate to be adhesively bonded;-   δ) Heating the flat substrate and/or the epoxy resin composition to    a temperature of 100-220° C., in particular 120-200° C., preferably    160-190° C.

As the result of heating the flat substrate and/or the epoxy resincomposition in step δ), the heat-activatable curing agent, i.e., thesilane or derivative thereof present on the surface of the flatsubstrate, is activated and brings about curing of the epoxy resin whichis thus in contact. This further heating of the epoxy resin compositionas the result of this curing reaction then brings about curing of theepoxy resin composition at a farther distance from the substratesurface, and so forth. Selective curing of the epoxy resin adhesivecomposition, starting from the substrate, may thus be carried out, whichsometimes results in an intentional and selectively producible gradientin the mechanical properties of the epoxy adhesive. If the surface ofthe substrate from step γ) is likewise coated or derivatized with silaneof formula (I), bonding composites may be obtained whose adhesive hasdifferent mechanical properties in the core than at the border for theparticular substrate.

The application of the silane of formula (I) to the surface of the flatsubstrate to be adhesively bonded in step α) may be carried out using asolvent, for example, and optionally in the presence of catalysts forhydrolysis of the Si—O—Z¹ groups of the silane of formula (I) and/orcondensation of silanol groups hydrolysis [sic]. Such catalysts are wellknown to persons skilled in the art in the field of silanes. A mixtureof a silane with a volatile solvent and optionally a catalyst, inparticular an organic acid, is typically used. Water, alcohols, ketones,aldehydes, carboxylic acid esters, and hydrocarbons in particular areused as solvent. The boiling point at standard pressure is in particular100° C. or less. Particularly preferred solvents for this purpose aremethanol, ethanol, isopropanol, hexane, heptane, and methyl ethylketone. The application may be carried out in particular by spraying,sprinkling, wiping, brushing, rolling, or dipping. The application ispreferably made with a small layer thickness, typically less than 100microns.

It is advantageous for a time period of at least 1 minute, typicallybetween 5 minutes and 30 minutes, to elapse between step α) and step β).This is particularly advantageous when the silane in step α) is appliedin a solvent. The solvent is able to completely or at leastsubstantially evaporate during this time period. The layer thickness ofthe silane present on the surface is preferably less than 100 micronsbefore the start of step β).

In an even more preferred embodiment, the substrate which is coated orderivatized with silane of formula (I) is a filler, preferably aninorganic filler, in particular an inorganic filler containing Ca and/orSi and/or Al atoms, preferably Si and/or Al atoms.

Particularly suited fillers of this type are calcium carbonate, silica,in particular pyrogenic silicic acid, kaolin, aluminum hydroxide,aluminum oxide, and alumoxane. Pyrogenic silicic acid and alumoxane aremost preferred. The filler is preferably dry, or at least moist only atthe surface. To obtain a homogeneous surface coating or derivatization,it is particularly advantageous when the filler is free-flowing.

The filler is coated or derivatized in the same manner as describedabove for the coating or derivatization of flat substrates in step a).However, the filler may also be stirred into the silane of formula (I),preferably into a mixture including silane (I), at least one of theabove-mentioned solvents, and optionally an above-mentioned catalyst,and then filtered off after the coating or derivatization. It is alsopreferable for a given time period of at least 1 minute, typicallybetween 5 minutes and 30 minutes, to elapse between application of thesilane of formula (I) and use of the filler in or for epoxy resincompositions.

It is important that for the substrate which is coated or derivatizedwith silane of formula (I), only the surface is coated or derivatized;i.e., any processes in which the silane of formula (I) is used directlyfor production of the filler, for example for the production of sol gelsor xerogels, are not the subject matter of the invention. Namely, it isimportant for the essence of the invention that only the surface iscoated or derivatized. On the one hand, existing fillers may be usedwhich are easily commercially obtainable and above all inexpensive. Onthe other hand, the coating or derivatization of the substrates is avery easily managed process, while the processes of in situ fillerproduction, for example for sol gels or xerogels, are very complicated,expensive, and susceptible to error.

These fillers are particularly preferably fine fillers; i.e., theaverage particle size of the filler is preferably less than 50 microns,in particular less than 1 micron. So-called nanofillers having anaverage particle size of 1 nanometer to 1 micron are most preferred.

The above-described silanes of formula (I) or fillers coated orderivatized with silane of formula (I) are in particular part of athermosetting epoxy resin composition.

Therefore, in a further aspect the present invention relates to athermosetting epoxy resin composition containing

-   -   at least one epoxy resin EH having an average of more than one        epoxide group per molecule;    -   at least one silane of formula (I) or a filler whose surface is        coated or derivatized with silane of formula (I), as described        in detail above.

The epoxy resin EH having an average of more than one epoxide group permolecule is preferably a liquid epoxy resin or a solid epoxy resin. Theterm “solid epoxy resin” is well known to a person skilled in the art inthe field of epoxides, and is used in contrast to “liquid epoxy resins.”The glass [transition] temperature of solid resins is above roomtemperature; i.e., the solid resins may be comminuted at roomtemperature to form free-flowing powders.

Preferred solid epoxy resins have formula (V):

In this regard, substituents R′ and R″ independently stand for either Hor CH₃. In addition, subscript s stands for a value of >1.5, inparticular 2 to 12.

Such solid epoxy resins are commercially available, for example fromDow, Huntsman, or Hexion.

Compounds of formula (V) having a subscript s between 1 and 1.5 arereferred to by those skilled in the art as “semisolid epoxy resins.” Forthe present invention they are also regarded as solid resins. However,solid epoxy resins in the narrower sense, i.e., for which subscript shas a value of >1.5, are preferred.

Preferred liquid epoxy resins have formula (VI):

In this regard, substituents R′ and R″ independently stand for either Hor CH₃. In addition, subscript r stands for a value of 0 to 1. It ispreferred that r stands for a value less than 0.2.

These are preferably diglycidyl ethers of bisphenol-A (DGEBA), ofbisphenol-F, and of bisphenol-A/F. Such liquid resins are available, forexample, as ARALDITE GY 250, ARALDITE PY 304, ARALDITE GY 282(Huntsman), D.E.R. 331 or D.E.R. 330 (Dow), or Epikote 828 (Hexion).

Also suited as epoxy resin EH are so-called novolacs, which inparticular have the following formula:

or CH₂, R1=H or methyl, and z=0 to 7.

These are in particular phenol or cresol novolacs (R2=CH₂).

Such epoxy resins are commercially available under the trade names EPNor ECN as well as TACTIX 556 from Huntsman, or under the D.E.N. productseries from Dow Chemical.

The epoxy resin EH preferably represents a liquid epoxy resin of formula(VI). In an even more preferred embodiment, the thermosetting epoxyresin composition contains at least one liquid epoxy resin of formula(VI) and at least one solid epoxy resin of formula (V).

The fraction of epoxy resin EH is preferably 10-85% by weight, inparticular 15-70% by weight, preferably 15-60% by weight, relative tothe weight of the thermosetting epoxy resin composition.

The fraction of the silane of formula (I) or of the filler whose surfaceis coated or derivatized with silane of formula (I) in the compositionis advantageously selected in such a way that the silane of formula (I)or the silane fraction of the filler is 0.001-20% by weight, inparticular 0.1-15% by weight, preferably 0.5-10% by weight, relative tothe weight of the thermosetting epoxy resin composition. For the sake ofclarity, it is noted at this point that in addition to the silane whichis present on the filler as silane of formula (I), the silane of formula(I) which is chemically bound to the filler is considered as “silane”for the term “silane fraction of the filler.” Thus, for determining thesilane fraction of the filler it is immaterial whether the silane at thesurface of the filler is free or chemically bound, i.e., whether thefiller is coated or derivatized with silane of formula (I).

The composition according to the invention also preferably contains atleast one heat-activatable curing agent B which in particular isselected from the group comprising dicyandiamide, guanamine, guanidine,aminoguanidine, and derivatives thereof; substituted ureas, inparticular 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea(chlortoluron),or phenyldimethyl ureas, in particularp-chlorophenyl-N,N-dimethylurea(monuron),3-phenyl-1,1-dimethylurea(fenuron),3,4-dichlorphenyl-N,N-dimethylurea(diuron), N,N-dimethylurea,N-isobutyl-N′,N′-dimethylurea,1,1′-(hexane-1,6-diyl)bis(3,3′-dimethylurea), and imidazoles, imidazolesalts, imidazolines, and amine complexes.

This heat-activatable curing agent B may be activated at the same or adifferent temperature as the silane of formula (I).

Dicyandiamide is particularly preferred as curing agent B.

The total fraction of curing agent B is advantageously 1-10% by weight,preferably 2-8% by weight, relative to the weight of the overallcomposition.

The thermosetting epoxy resin composition may also contain a thixotropicagent C based on a urea derivative. The urea derivative in particular isa reaction product of an aromatic monomeric diisocyanate with analiphatic amine compound. It is also possible to react multipledifferent monomeric diisocyanates with one or more aliphatic aminecompounds, or to react a monomeric diisocyanate with multiple aliphaticamine compounds. The reaction product of 4,4′-diphenylmethylenediisocyanate (MDI) with butylamine has proven to be particularlyadvantageous.

The urea derivative is preferably present in a carrier material. Thecarrier material may be a softener, in particular a phthalate or anadipate, preferably a diisodecyl phthalate (DIDP) or dioctyl adipate(DOA). The carrier agent may also be a nondiffusing carrier agent. Thisis preferred in order to ensure minimum migration of unreactedconstituents after curing. Blocked polyurethane prepolymers arepreferred as nondiffusing carrier agents.

The preparation of such preferred urea derivatives and carrier materialsis described in detail in patent application US 2002/0007003 A1, thecontent of which is hereby incorporated by reference. The carriermaterial is advantageously a blocked polyurethane prepolymer, inparticular obtained by reacting a trifunctional polyether polyol withIPDI, followed by blocking of the end-position isocyanate groups withε-caprolactam.

The total proportion of thixotropic agent C is advantageously 0-40% byweight, preferably 5-25% by weight, relative to the weight of theoverall composition. The ratio of the weight of the urea derivative tothe weight of the optionally present carrier agent is preferably 2/98 to50/50, in particular 5/95 to 25/75.

It has also been shown to be particularly advantageous when thethermosetting single-component epoxy resin composition also contains atleast one impact modifier D.

The impact modifiers D may be solid or liquid.

It has been shown that the impact modifier D is advantageously selectedfrom the group comprising blocked polyurethane polymers, liquid rubbers,epoxy resin-modified liquid rubbers, block copolymers, and core-shellpolymers, in particular in a quantity of 0.1-50% by weight, inparticular 0.5-35% by weight, preferably 1-20% by weight, relative tothe weight of the thermosetting epoxy resin composition.

In one embodiment, this impact modifier D is a liquid rubber D1 which isa carboxyl- or epoxide-terminated acrylonitrile/butadiene copolymer or aderivative thereof. Such liquid rubbers are commercially available, forexample under the names HYPRO (formerly HYCAR) CTBN, CTBNX, and ETBNfrom Nanoresins AG, Germany, or from Emerald Performance Materials LLC.Elastomer-modified prepolymers containing in particular epoxy groups, asmarketed under the product line POLYDIS, preferably the product linePOLYDIS 36. from Struktol (Schill+Seilacher Groups, Germany), or underthe product line Albipox (Nanoresins, Germany), are suitable asderivatives.

In another embodiment, the impact modifier D is a polyacrylate liquidrubber D2 which is fully miscible with liquid epoxy resins and whichdoes not demix to form microdroplets until the epoxy resin matrix hascured. Such polyacrylate liquid rubbers are available, for example,under the trade name 20208-XPA from Rohm and Haas.

It is clear to one skilled in the art that mixtures of liquid rubbersmay of course also be used, in particular mixtures of carboxyl- orepoxide-terminated acrylonitrile/butadiene copolymers or derivativesthereof with epoxide-terminated polyurethane prepolymers.

In another embodiment, the impact modifier D is a solid impact modifierwhich is an organic ion-exchanged layered mineral DE1.

The ion-exchanged layered mineral DE1 may be either a cation-exchangedlayered mineral DE1c or an anion-exchanged layered mineral DE1a.

The cation-exchanged layered mineral DE1c is obtained from a layeredmineral DE1′ in which at least a portion of the cations have beenexchanged with organic cations. Examples of such cation-exchangedlayered minerals DE1c are in particular those mentioned in U.S. Pat. No.5,707,439 or U.S. Pat. No. 6,197,849. The cited documents also describethe method for producing these cation-exchanged layered minerals DE1c. Alayered silicate is preferred as layered mineral DE1′. The layeredmineral DE1′ is particularly preferably a phyllosilicate, in particulara bentonite, as described in U.S. Pat. No. 6,197,849, column 2, line 38to column 3, line 5. A layered mineral DE1′ such as kaolinite, amontmorillionite, a hectorite, or an illite has been shown to beparticularly suitable.

At least a portion of the cations in the layered mineral DE1′ arereplaced by organic cations. Examples of such cations includen-octylammonium, trimethyldodecylammonium, dimethyldodecylammonium, orbis(hydroxyethyl)octadecylammonium, or similar derivatives of amineswhich may be obtained from natural fats and oils; or guanidinium cationsor amidinium cations; or cations of the N-substituted derivatives ofpyrrolidine, piperidine, piperazine, morpholine, or thiomorpholine; orcations of 1,4-diazobicyclo[2.2.2]octane (DABCO) and1-azobicyclo[2.2.2]octane; or cations of N-substituted derivatives ofpyridine, pyrrole, imidazole, oxazole, pyrimidine, quinoline,isoquinoiline, pyrazine, indole, benzimidazole, benzoxaziole, thiazole,phenazine, and 2,2′-bipyridine. Also suitable are cyclic amidiniumcations, in particular those disclosed in U.S. Pat. No. 6,197,849 incolumn 3, line 6 to column 4, line 67. Compared to linear ammoniumcompounds, cyclic ammonium compounds are characterized by increasedthermal stability since they are not able to undergo the thermalHoffmann degradation reaction.

Preferred cation-exchanged layered minerals DE1c are known to oneskilled in the art under the term “organoclay” or “nanociay,” and arecommercially available, for example, under the group names TIXOGEL orNANOFIL (Südchemie), CLOISITE (Southern Clay Products), NANOMER (NanocorInc.), or GARMITE (Rockwood).

The anion-exchanged layered mineral DE1a is obtained from a layeredmineral DE1″ in which at least a portion of the anions have beenexchanged with organic anions. One example of such an anion-exchangedlayered mineral DE1a is a hydrotalcite DE1″, in which at least a portionof the carbonate anions of the intermediate layers have been exchangedwith organic anions.

It is also possible for the composition to contain both acation-exchanged layered mineral DE1c and an anion-exchanged layeredmineral DE1a.

In another embodiment, the impact modifier D is a solid impact modifierwhich is a block copolymer DE2. The block copolymer DE2 is obtained froman anionic polymerization or controlled radical polymerization ofmethacrylate with at least one further monomer containing an olefinicdouble bond. Particularly preferred as monomers containing an olefinicdouble bond are monomers in which the double bond is directly conjugatedwith a heteroatom or with at least one further double bond. Particularlysuited are monomers selected from the group comprising styrene,butadiene, acrylonitrile, and vinyl acetate. Acrylate/styrene/acrylicacid copolymers (ASA), obtainable under the name GELOY 1020 from GEPlastics, for example, are preferred.

Particularly preferred block copolymers DE2 are block copolymers ofmethyl methacrylate, styrene, and butadiene. Such block copolymers areavailable, for example, as triblock copolymers under the group name SBMfrom Arkema.

In another embodiment, impact modifier D is a core-shell polymer DE3.Core-shell polymers are composed of an elastic core polymer and a rigidshell polymer. Particularly suited core-shell polymers are composed of acore of elastic acrylate polymer or butadiene polymer which encloses arigid shell of an inflexible thermoplastic polymer. This core-shellstructure is formed either spontaneously as the result of demixing of ablock copolymer, or is specified by the polymerization control as latexor suspension polymerization with subsequent grafting. Preferredcore-shell polymers are so-called MBS polymers, which are commerciallyavailable under the trade names CLEARSTRENGTH from Atofina, PARALOIDfrom Rohm and Haas, or F-351 from Zeon.

Core-shell polymer particles which are already present as dried polymerlatex are particularly preferred. Examples of such include GENIOPERLM23A from Wacker, having a polysiloxane core and an acrylate shell,radiation-crosslinked rubber particles of the NEP series manufactured byEliokem, Nanoprene from Lanxess, or Paraloid EXL from Rohm and Haas.

Further comparable examples of core-shell polymers are marketed underthe name ALBIDUR from Nanoresins AG, Germany.

Also suitable are nanoscale silicates in an epoxy matrix, marketed underthe trade name NONOPDX from Nanoresins AG, Germany.

In another embodiment, the impact modifier D is a product DE4 of thereaction of a carboxylated solid nitrile rubber with excess epoxy resin.

In another embodiment, the impact modifier D is a blocked polyurethanepolymer of formula (IV).

In this regard, m and m′ each stand for values between 0 and 8, with thecondition that m+m′ stands for a value from 1 to 8.

m is preferably different from 0.

In addition, Y¹ stands for a linear or branched polyurethane polymerPU1, terminated by m+m′ isocyanate groups, after removal of allend-position isocyanate groups.

Y² independently stands for a blocking group which cleaves at atemperature above 100° C.

Y³ independently stands for a group of formula (IV).

In this regard, R⁴ stands for a radical of an aliphatic, cycloaliphatic,aromatic, or araliphatic epoxy, containing a primary or secondaryhydroxyl group, after removal of the hydroxide and epoxy groups, and pstands for the values 1, 2, or 3.

In the present document, “araliphatic radical” refers to an aralkylgroup, i.e., an alkyl group substituted with aryl groups (see “Aralkyl,”Römpp, CD Römpp's Chemical Lexicon, Version 1, Stuttgart/New York, GeorgThieme Verlag 1995).

In particular, Y² independently stands for a substituent selected fromthe group comprising

In this regard R⁵, R⁶, R⁷, and R⁸ each independently stand for an alkyl,cycloalkyl, aralkyl, or arylalkyl group, or R⁵ together with R⁶, or R⁷together with R⁸, forms a part of a 4- to 7-membered ring which isoptionally substituted.

In addition, R⁹, R^(9′), and R¹⁰ each independently stand for an alkyl,aralkyl, or arylalkyl group or for an alkyloxy, aryloxy, or aralkyloxygroup, and R¹¹ stands for an alkyl group.

R¹², R¹³, and R¹⁴ each independently stand for an alkylene groupcontaining 2 to 5 C atoms, and optionally having double bonds or beingsubstituted, or stand for a phenylene group or a hydrogenated phenylenegroup, and R¹⁵, R¹⁶, and R¹⁷ each independently stand for H or for analkyl, aryl, or aralkyl group.

Lastly, R¹⁸ stands for an aralkyl group or for a mononuclear substitutedor unsubstituted aromatic group which optionally contains aromatichydroxyl groups. On the one hand, R¹⁸ in particular represents phenolsor bisphenols after removal of a hydroxyl group. Preferred examples ofsuch phenols and bisphenol are in particular phenol, cresol, resorcinol,pyrocatechol, cardanol(3-pentadecenylphenol (from cashew shell oil)),nonylphenol, phenols reacted with styrene or dicyclopentadiene,bis-phenol-A, bis-phenol-F, and 2,2′-diallyl bisphenol-A.

On the other hand, R¹⁸ in particular represents hydroxybenzyl alcoholand benzyl alcohol after removal of a hydroxyl group.

If R⁵, R⁶, R⁷, R⁸, R⁹, R^(9′), R¹⁰, R¹¹, R¹⁵, R¹⁶, or R¹⁷ stands for analkyl group, this group in particular is a linear or branchedC₁-C₂₀-alkyl group.

If R⁵, R⁶, R⁷, R⁸, R⁹, R^(9′), R¹⁰, R¹⁵, R¹⁶, R¹⁷, or R¹⁸ stands for anaralkyl group, this group in particular is an aromatic group, inparticular a benzyl group, bonded via methylene.

If R⁵, R⁶, R⁷, R⁸, R⁹, R^(9′), or R¹⁰ stands for an alkylaryl group,this group in particular is a C₁-C₂₀-alkyl group, for example tolyl orxylyl, bonded via phenylene.

Particularly preferred Y² radicals are radicals selected from the groupcomprising

In this regard, the radical Y stands for a saturated or olefinicallyunsaturated hydrocarbon radical containing 1 to 20 C atoms, inparticular 1 to 15 C atoms. AIlyl, methyl, nonyl, dodecyl, or anunsaturated C₁₅-alkyl radical containing 1 to 3 double bonds isparticularly preferred as Y.

The radical X′ stands for H or for an alkyl, aryl, or aralkyl group, inparticular for H or methyl.

The subscripts z′ and z″ stand for the values 0, 1, 2, 3, 4, or 5, withthe condition that the sum z′+z″ is a value between 1 and 5.

The blocked polyurethane polymer of formula (IV) is prepared by[reacting] linear or branched polyurethane polymers PU1, terminated bythe isocyanate groups, with one or more isocyanate-reactive compoundsY²H and/or Y³H. If more than one such isocyanate-reactive compound isused, the reaction may be carried out sequentially or using a mixture ofthese compounds.

The reaction is carried out in such a way that the one or moreisocyanate-reactive compounds Y²H and/or Y³H are used stoichiometricallyor in stoichiometric excess to ensure that all NCO groups are reacted.

The isocyanate-reactive compound Y³H is a monohydroxyl epoxy compound offormula (IVa).

If more than one such monohydroxyl epoxy compound is used, the reactionmay be carried out sequentially or using a mixture of these compounds.

The monohydroxyl epoxy compound of formula (IVa) contains 1, 2, or 3epoxy groups. The hydroxyl group of this monohydroxyl epoxy compound(IVa) may represent a primary or a secondary hydroxyl group.

Such monohydroxyl epoxy compounds may be prepared, for example, byreacting polyols with epichlorohydrin. Depending on the reactioncontrol, the corresponding monohydroxyl epoxy compounds are also formedin various concentrations as by-products in the reaction ofpolyfunctional alcohols with epichlorohydrin. These by-products may beisolated using customary separating operations. However, it is generallysufficient to use the product mixture, composed of polyol, which iscompletely and partially reacted to form the glycidyl ether, obtained inthe glycidylization reaction of polyols. Examples of suchhydroxyl-containing epoxides are butanediol monoglycidyl ether (presentin butanediol diglycidyl ether), hexanediol monoglycidyl ether (presentin hexanediol diglycidyl ether), cyclohexanedimethanol glycidyl ether,trimethylolpropane diglycidyl ether (present as a mixture intrimethylolpropane triglycidyl ether), glycerin diglycidyl ether(present as a mixture in glycerin triglycidyl ether), and pentaerythritetriglycidyl ether (present as a mixture in pentaerythrite tetraglycidylether). Preferably used is trimethylolpropane triglycidyl ether, whichis present in a relatively high proportion in commonly preparedtrimethylolpropane triglycidyl ethers.

However, other similar hydroxyl-containing epoxides, in particularglycidol, 3-glycidyloxybenzyl alcohol, or hydroxymethylcyclohexeneoxide, may also be used. Also preferred is the β-hydroxy ether offormula (IVb), which is contained in proportions up to approximately 15%in commercially available liquid epoxy resins produced from bisphenol-A(R═CH₃) and epichlorohydrin, as well as the corresponding β-hydroxyethers of formula (IVb), which are formed when bisphenol-F (R═H) or themixture of bisphenol-A and bisphenol-F is reacted with epichlorohydrin.

Also preferred are distillation residues which are produced in thepreparation of high-purity distilled liquid epoxy resins. Suchdistillation residues have a concentration of hydroxyl-containingepoxides that is one to three times higher than in commerciallyavailable undistilled liquid epoxy resins. In addition, various epoxidesmay be used which contain a β-hydroxy ether group, prepared by thereaction of (poly-)epoxides with a deficit of monofunctionalnucleophiles such as carboxylic acids, phenols, thiols, or secondaryamines.

The R⁴ radical particularly preferably is a trifunctional radical offormula

where R stands for methyl or H.

The free primary or secondary OH functionality of the monohydroxylepoxide compound of formula (IVa) allows an efficient reaction withterminal isocyanate groups of polymers without having to usedisproportionate excesses of the epoxide component.

The polyurethane polymer PU1, based on Y¹, may be prepared from at leastone diisocyanate or triisocyanate and at least one polymer Q_(PM)containing end-position amino, thiol, or hydroxyl groups, and/or from anoptionally substituted polyphenol Q_(PP).

Examples of suitable diisocyanates include aliphatic, cycloaliphatic,aromatic, or araliphatic diisocyanates, in particular those previouslymentioned as diisocyanate of formula (II a). HDI, IPDI, MDI, or TDI arepreferred.

Examples of suitable triisocyanates are trimers or biurets of aliphatic,cycloaliphatic, aromatic, or araliphatic diisocyanates, in particularthe isocyanates and biurets previously mentioned as polyisocyanates offormula (II a).

Of course, suitable mixtures of di- or triisocyanates may also be used.

Polymers Q_(PM) containing two or three end-position amino, thiol, orhydroxyl groups are particularly suited as polymers Q_(PM) containingend-position amino, thiol, or hydroxyl groups.

Particularly suited as polymers Q_(PM) are those disclosed, for example,in WO 20081049857 A1, in particular as Q_(PM) on page 7, line 25 to page11, line 20, the content of which is in particular incorporated byreference.

The polymers Q_(PM) advantageously have an equivalent weight of300-6000, in particular 600-4000, preferably 700-2200, g/equivalentNCO-reactive groups.

Particularly suited as polymers Q_(PM) are polyoxyalkylene polyols, alsoreferred to as polyether polyols, hydroxy-terminated polybutadienepolyols, styrene-acrylonitrile grafted polyether polyols,polyhydroxy-terminated acrylonitrile/butadiene copolymers, polyesterpolyols, and polycarbonate polyols.

Amphiphilic block copolymers containing at least one hydroxyl group, inparticular those marketed under the trade name FORTEGRA, in particularFORTEGRA 100, from Dow Chemical, have proven to be particularly suitableas polymers Q_(PM).

Particularly suited as polyphenol Q_(PP) are bis-, tris-, andtetraphenols. These are understood to mean not only pure phenols butalso optionally substituted phenols. Various types of substitution maybe used. This is understood in particular to mean a substitutiondirectly at the aromatic nucleus to which the phenolic OH group isbound. In addition, the term “phenols” refers not only to mononucleararomatics, but also to polynuclear or condensed aromatics orheteroaromatics which contain the phenolic OH group directly on thearomatic or heteroaromatic.

The bis- and trisphenols are particularly suited. Examples of suitablebisphenols or trisphenols include 1,4-dihydroxybenzene,1,3-dihydroxybenzene, 1,2-dihydroxybenzene, 1,3-dihydroxytoluene,3,5-dihydroxybenzoate, 2,2-bis(4-hydroxyphenyl)propane (=bisphenol-A),bis(4-hydroxyphenyl)methane (=bisphenol-F), bis(4-hydroxyphenyl)sulfone(=bisphenol-S), naphthoresorcinoi, dihydroxynaphthalene,dihydroxyanthraquinone, dihydroxybiphenyl,3,3-bis(p-hydroxyphenyl)phthalide,5,5-bis(4-hydroxyphenyl)hexahydro-4,7-methanoindan, phenolpthalein,fluorescein,4,4′-[bis-(hydroxyphenyl)-1,3-phenylene-bis-(1-methylethyldene)](=bisphenol-M),4,4′-[bis-(hydroxyphenyl)-1,4-phenylene-bis-(1-methylethylidene)](=bisphenol-P), 2,2′-diallyl bisphenol-A, diphenols and dicresolsprepared by reacting phenols or cresols with di-isopropylidenebenzene,phloroglucin, gallic acid esters, phenol or cresol novolacs having an OHfunctionality of 2.0 to 3.5, and all isomers of the above-mentionedcompounds.

Particularly suited as impact modifier D which is optionally present inthe composition are those disclosed in the following articles or patentdocuments, whose content is hereby incorporated by reference: EP 0 308664 A1, in particular formula (I), especially page 5, line 14 to page13, line 24; EP 0 338 985 A1, EP 0 353 190 A1, WO 00/20483 A1, inparticular formula (I), especially page 8, line 18 to page 12, line 2;WO 01/94492 A1, in particular the reaction products referred to as D)and E), especially page 10, line 15 to page 14, line 22; WO 03/078163A1, in particular the acrylate-terminated polyurethane resin referred toas B), especially page 14, line 6 to page 14, line 35; WO 2005/007766A1, in particular formula (I) or (II), especially page 4, line 5 to page11, line 20; EP 1 728 825 A1, in particular formula (I), especially page3, line 21 to page 4, line 47; WO 2006/052726 A1, in particular theamphiphilic block copolymer referred to as b), especially page 6, line17 to page 9, line 10; WO 2006/052729 A1, in particular the amphiphilicblock copolymer referred to as b), especially page 6, line 25 to page10, line 2; T. J. Hermel-Davidock et al., J. Polym. Sol. Part B: Polym.Phys. 2007, 45, 3338-3348, in particular the amphiphilic blockcopolymers, especially page 3339, column 2 to page 3341, column 2; WO2004/055092 A1, in particular formula (I), especially page 7, line 28 topage 13, line 15; WO 2005/007720 A1, in particular formula (I),especially page 8, line 1 to page 17, line 10; WO 2007/020266 A1, inparticular formula (I), especially page 3, line 1 to page 11, line 6; WO2008/049857 A1, in particular formula (I), especially page 3, line 5 topage 6, line 20; WO 2008/049858 A1, in particular formulas (I) and (II),especially page 6, line I to page 12, line 15; WO 2008/049859 A1, inparticular formula (I), especially page 6, line 1 to page 11, line 10;WO 20,08/049860 A1, in particular formula (I), especially page 3, line 1to page 9, line 6; and DE-A-2 123 033, US 2008/0076886 A1, WO2008/016889, and WO 2007/025007.

It has been shown that multiple impact modifiers are advantageouslypresent in the composition.

The fraction of impact modifiers D is advantageously used in a quantityof 1-45% by weight, in particular 1-35% by weight, relative to theweight of the composition.

In another preferred embodiment, the composition also contains at leastone filler F. Preferred as such are mica, talc, kaolin, wollastonite,feldspar, syenite, chlorite, bentonite, montmorillonite, calciumcarbonate (precipitated or pulverized), dolomite, quartz, silicic acids(pyrogenic or precipitated), cristobalite, calcium oxide, aluminumhydroxide, magnesium oxide, hollow ceramic beads, hollow glass beads,organic hollow beads, glass beads, and colored pigments. The organicallycoated as well as uncoated forms, which are commercially available andknown to one skilled in the art, are also intended as filler F.

Functionalized alumoxanes as described in U.S. Pat. No. 6,322,890, forexample, represent another example.

The overall fraction of the total filler F is advantageously 3-50% byweight, preferably 5-35% by weight, in particular 5-25% by weight,relative to the weight of the overall composition.

In another preferred embodiment the composition contains a physical orchemical blowing agent, such as those available, for example, under thetrade names EXPANCEL from Akzo Nobel or CELOGEN from Chemtura. Theproportion of blowing agent is advantageously 0.1-3% by weight, relativeto the weight of the composition.

In another preferred embodiment, the composition also contains areactive diluent G containing at least one epoxide group. These reactivediluents G are in particular the following:

-   -   Glycidyl ethers of monofunctional saturated or unsaturated,        branched or unbranched, cyclic or open-chain C₄-C₃₀ alcohols, in        particular selected from the group comprising butanol glycidyl        ether, hexanol glycidyl ether, 2-ethylhexanol glycidyl ether,        allyl glycidyl ether, tetrahydrofurfuryl and furfuryl glycidyl        ethers, and trimethoxysilyl glycidyl ether.    -   Glycidyl ethers of difunctional saturated or unsaturated,        branched or unbranched, cyclic or open-chain C₂-C₃₀ alcohols, in        particular selected from the group comprising ethylene glycol,        butanediol, hexanediol, and octanediol gylcidyl ethers,        cyclohexanedimethanol digylcidyl ether, and neopentyl glycol        diglycidyl ether.    -   Glycidyl ethers of tri- or polyfunctional, saturated or        unsaturated, branched or unbranched, cyclic or open-chain        alcohols such as epoxidized castor bean oil, epoxidized        trimethylolpropane, epoxidized pentaerythrol, or polyglycidyl        ethers of aliphatic polyols such as sorbitol, glycerin, or        trimethylolpropane.    -   Glycidyl ethers of phenol and aniline compounds, in particular        selected from the group comprising phenyl glycidyl ether, cresyl        glycidyl ether, p-tert-butylphenyl glycidyl ether, nonylphenol        glycidyl ether, 3-n-pentadecenyl glycidyl ether (from cashew        shell oil), N,N-diglycidylaniline, and the triglycidyl [ether]        of p-aminophenol.    -   Epoxidized amines such as N,N-diglycidylcyclohexylamine.    -   Epoxidized mono- or dicarboxylic acids, in particular those        selected from the group comprising neodecanoic acid glycidyl        esters, methacrylic acid glycidyl esters, benzoic acid glycidyl        esters, phthalic acid, tetra- and hexahydrophthalic acid        diglycidyl esters, and diglycidyl esters of dimeric fatty acids,        and terephthalic acid and trimellitic acid gylcidyl esters.    -   Epoxidized di- or trifunctional, low- to high-molecular        polyether polyols, in particular polyethylene glycol-diglycidyl        ether or polypropylene glycol-diglycidyl ether.

Particularly preferred are hexanediol diglycidyl ether, cresyl glycidylether, p-tert-butylphenyl glycidyl ether, polypropylene glycoldiglycidyl ether, and polyethylene glycol diglycidyl ether.

The total fraction of reactive diluent G, containing the epoxide groups,is advantageously 0.1-20% by weight, preferably 1-8% by weight, relativeto the weight of the overall composition.

The composition may include further constituents, in particularcatalysts, stabilizers, especially heat and/or light stabilizers,thixotropic agents, softeners, solvents, mineral or organic fillers,blowing agents, dyes and pigments, anticorrosion agents, surfactants,antifoaming agents, and bonding agents.

Particularly suited as softeners are phenol alkyl sulfonate andN-butylbenzenesulfonamide, which are commercially available from Bayeras MESAMOLL and DELLATOL BBS, respectively.

Particularly suited as stabilizers are optionally substituted phenolssuch as butylhydroxytoluene (BHT) or WINGSTAY T (Elikem), stericallyhindered amines, or N-oxyl compounds such as TEMPO (Evonik).

The described thermosetting epoxy resin compositions after curing arecharacterized by high impact strength and a glass transition temperaturetypically greater than 100° C.

It has been shown that the described thermosetting epoxy resincompositions are particularly suited as single-component adhesives. Sucha single-component adhesive has many applications. In particular,thermosetting single-component adhesives may thus be obtained which arecharacterized by high impact strength. Such adhesives are necessary forbonding heat-stable materials. Heat-stable materials are understood tomean materials which are dimensionally stable at a curing temperature of100-220° C., preferably 120-200° C., at least during the curing time.These involve in particular metals, and plastics such as ABS, polyamide,and polyphenylene ether, composite materials such as SMC, GFRPunsaturated polyester, and epoxy or acrylate composites. The applicationin which at least one material is a metal is preferred. A particularlypreferred use is the adhesive bonding of identical or different metals,in particular for body shells in the automotive industry. The preferredmetals are primarily steel, in particular electrogalvanized steel,hot-dip galvanized steel, lubricated steel, Bonazinc-coated steel, andsubsequently phosphated steel, as well as aluminum, in particular in thevariants typically used in automobile manufacture.

Such an adhesive is in particular first contacted with the materials tobe bonded, at a temperature between 10° C. and 80° C., in particularbetween 10° C. and 60° C., and is subsequently cured at a temperature oftypically 100-220° C., preferably 120-200° C.

A further aspect of the present invention relates to a method foradhesively bonding heat-stable substrates, having the following steps:

-   -   i) Applying a thermosetting epoxy resin composition, as        described in detail above, to the surface of a heat-stable        substrate S1, in particular a metal;    -   ii) Contacting the applied thermosetting epoxy resin composition        with the surface of a further heat-stable substrate S2, in        particular a metal;    -   iii) Heating the epoxy resin composition to a temperature of        100-220° C., in particular 120-200° C., preferably 160-190° C.;    -   wherein substrate S2 is composed of a material which is        identical to or different from substrate S1.

Substrate S2 is composed of a material which is identical to ordifferent from substrate S1.

A bonded article results from such a method for adhesively bondingheat-stable materials. Such an article is preferably a vehicle or amounted part of a vehicle.

Of course, in addition to thermosetting adhesives, sealants or coatingsmay be realized using a composition according to the invention.Furthermore, the compositions according to the invention are suitablefor other applications besides automobile manufacture. Mentioned inparticular are related applications in the manufacture of transportmeans such as ships, trucks, buses, or rail vehicles, or in themanufacture of consumer goods such as washing machines, for example.

The materials adhesively bonded using a composition according to theinvention are used at temperatures that are typically between 120° C.and −40° C., preferably between 100° C. and −40° C., in particularbetween 80° C. and −40° C.

It is particularly preferred to use the thermosetting epoxy resincomposition according to the invention as a thermosetting adhesive forbody shells in vehicle manufacture.

A further aspect of the present invention thus relates to a cured epoxyresin composition which is obtained by heating a thermosetting epoxyresin composition described in detail above.

It has been shown that compositions containing silanes of formula (I),in particular of formula (I a), allow a large reduction in the curingtemperature without great impairment of their storage stability. It isthus possible to meet the desired requirements of the industry for areduction in the curing temperature to below 180° C., even after a veryshort time, typically 10 to 15 minutes. It has also been shown that highglass transition temperatures of greater than 100° C. as well asincreased impact strengths may be achieved, which are required inparticular for use of these single-component thermosetting epoxy resincompositions as body shell adhesives for vehicle manufacture.

Furthermore, it has been shown that the silanes of formula (I) result inincreased adhesion to various subsurfaces. This is the case not only inthe area of epoxy adhesives or coatings, but in other areas as well.

Thus, silanes of formula (I) may also be used in general as bondingagents, for example in primers for adhesives, in particular forwet-curing single-component polyurethane adhesives.

EXAMPLES Preparation of 1,1-dimethyl-3-(3-(trimethoxysilyl)propyl)urea

5.0 g (46.5 mmol) N,N-dimethylcarbamoyl chloride (Sigma-Aldrich,Switzerland) and 40 ml, dried dioxane (Sigma-Aldrich, Switzerland) wereadded to a 250-mL round-bottom two-neck flask equipped with a refluxcooler. 4.71 g (46.5 mmol) triethylamine (Sigma-Aldrich, Switzerland)and 8.34 g (46.5 mmol) 3-aminopropyltrimethoxysilane (Silquest A-1110,Momentive Performance Materials Inc., USA) were added dropwise undernitrogen, with stirring. After the exothermic reaction subsided, theresulting whitish suspension was stirred at 90° C. for 3 hours. Agradual color change to orange was observed. After cooling to 50° C.,the solid was separated by double filtration, and the solvent wasremoved at 60° C. for 1 hour on a rotary evaporator. 9.6 g of thedesired silane was obtained as a brown liquid. The silane was designatedas DMA1100 and used without further purification.

The infrared spectrum of DMA1100 was measured on a Perkin-Elmer 1600FT-IR instrument (ATR measuring unit using ZnSe crystal, absorptionbands expressed in wave numbers (cm⁻¹), measurement window: 4000-650cm⁻¹):

-   -   IR (cm⁻¹): 3343 v(NH), 2938 v(CH), 2838 v(CH), 1631 v(CO), 1532        δ(CNH)+v(CN), 1268 v(CN)+δ(CNH), 1226 v(CN)+δ(CNH), 1074        v(SiO)+v(SiC), 805 v(SiO)+v(SiC), 767 v(SiO)+v(SiC).

3,3″-(4-Methyl-1,3-phenylene)bis(1,1-dimethylurea) (“HSRef.1”)

3,3′-(4-Methyl-1,3-phenylene)bis(1,1-dimethylurea) from Sigma-Aldrich,Switzerland, was used. This urea compound is not according to theinvention.

Preparation of SMI Impact Modifier

150 g poly-THF2000 (OH number 57 mg/g KOH, BASF) and 150 g Liquiflex H(OH number 46 mg/g KOH, Krahn) were dried for 30 minutes at 105° C.under vacuum. After the temperature was reduced to 90° C., 64.0 gisophorone diisocyanate (Evonik) and 0.13 g dibutyltin dilaurate wereadded. The reaction was carried out under vacuum at 90° C. until the NCOcontent was constant at 3.30% after 2.5 h (calculated NCO content:3.38%). 103.0 g CARDOLITE NC-700 (Cardanol, Cardolite) was then added asblocking agent. Stirring of the mixture continued under vacuum at 105°C. until the NCO content had dropped below 0.1% after 3.5 h.

Preparation of Thermosetting Epoxy Resin Compositions

Comparative compositions Ref.1 and Ref.2 as well as composition 1according to the invention as presented in Table 1 were prepared. Ineach case the constituents are given in parts by weight. The ureacompounds DMA1100 and HSRef.1 were used in such a way that theycontained the same quantities of urea groups.

Test Methods:

Tensile Shear Strength (TSS) (DIN EN 1465)

The test specimens were produced from the described examplecompositions, using electrogalvanized DC04 steel (eloZn) havingdimensions of 100×25×0.8 mm, with an adhesive surface of 25×10 mm and alayer thickness of 0.3 mm. Curing was performed for 30 min at 175° C.The tensile speed was 10 mm/min. The value thus measured is designatedas “TSS_(175° C.)”.

To compare the underbake tolerance, tensile shear strength testspecimens were also correspondingly produced and measured, wherein thecuring occurred by heating for 15 minutes at 165° C. (“TSS_(165° C.)”).

Cleavage Resistance Under Impact Loading (ISO 11343)

The test specimens were produced from the described examplecompositions, using electrogalvanized DC04 steel (eloZn) havingdimensions of 90×20×0.8 mm, with an adhesive surface of 20×30 mm and alayer thickness of 0.3 mm. Curing was performed for 30 min at 180° C.The cleavage resistance under impact loading was measured in each caseat room temperature. The impact speed was 2 m/s. The area under themeasurement curve (from 25% to 90% according to ISO 11343) is given asthe fracture energy (FE) in joules.

Viscosity

The adhesive samples were measured on a Bohlin CVO 120 viscosimeter,plate/plate (diameter 25 mm, gap width 1 mm), frequency 5 Hz, 0.01deflection, temperature 23-53° C., 10° C./min. The viscosity wasdetermined from the measured curve as complex viscosity at 25° C.

Storage Stability

An expedited procedure at elevated temperature was used for determiningthe storage stability at room temperature. The viscosity of thecompositions at room temperature was measured immediately afterproduction (“η₀”) and compared to the value at room temperature afterstorage in a tightly sealed container for 7 days at 60° C. (“η₆₆ ”). Thevalue Δη according to formula (η_(Δ)/η₀)−1 was determined as theapparent measure of the storage stability.

Glass Transition Temperature (T_(g))

The glass transition temperature was determined by DSC using a MettlerDSC822^(e) instrument. In each case 10-20 mg of the compositions wereweighed into an aluminum crucible. After the sample had cured in the DSCfor 30 min at 175° C., it was cooled to −20° C. and then heated to 150°C. at a heating rate of 10° C./min. The glass transition temperature wasdetermined as the inflection point from the measured DSC curve, usingDSC software.

Curing Characteristics

DSC was performed on a Mettler DSC 822^(E) instrument for each of theepoxy resin compositions mixed in this manner (heating from 25° C. to250° C., with a heating rate of 10 K/minute). The measured curve wasused to determine the maximum of the reaction peak as T_(Peak-DSC) aswell as the onset T_(Onset-DSC) calculated from the curve.

TABLE 1 Compositions and results. Ref1 Ref2 1 D.E.R. 331 (Dow) 40.0 40.040.0 Bisphenol-A digylcidyl ether, liquid epoxy resin Polypox R7 (UPPC)3.0 3.0 3.0 tert-Butylphenyl glycidyl ether POLYDIS 3614 (Struktol) 15.015.0 15.0 Epoxy resin-modified acrylonitrile/ butadiene copolymer (CTBN)SM1 15.0 15.0 15.0 HSRef, 1 0.51 DMA1100 0.97 Dicyandiamide (Degussa)4.0 4.0 4.0 Filler mixture 19.0 19.0 19.0 TSS_(175° C.) [MPa] 21.4 21.718.7 TSS_(165° C.) [MPa] 0.0* 20.1 18.4 FE¹ at 23° C. [J] 14.2 16.1 10.7η₀ [mPas] 395 350 412 η_(Δ) [mPas] 395 1340 517 Δη [%] 0 283 25 T_(g) [°C.] 106 105 104 T_(Onset-DSC) [° C.] 189 172 168 T_(Peak-DSC) [° C.] 198181 178 ¹FE = fracture energy. *Adhesive did not cure.

The results from Table 1 show that Comparative Example Ref1 hasessentially the same storage stability as for Example 1, but in contrastto Example I did not cure at lower curing temperatures (165° C., 15min). Comparative Example Ref2 shows that curing at lower temperaturesis possible using the aromatic urea HSRef.1, but such a composition isnot stable under storage. On the other hand, Example 1 is stable understorage and is also curable at lower temperatures. The curing at lowertemperatures is also apparent from the lower DSC values (T_(Peak-DSC)and T_(Onset-DSC)).

In addition, the values from Table 1 show that in addition to a highglass transition temperature and high impact strength, Example 1 hasgood mechanical properties which are very well suited for use as bodyshell adhesive for vehicle manufacture.

1. A silane of formula (I), for a curing agent of epoxy resins, which is activatable at elevated temperature,

wherein A is an optionally branched alkylene group containing 1 to 4 C atoms, or a phenylene group; wherein Z¹ is H or an alkyl group containing 1 to 4 C atoms; wherein Z² is H, a phenyl group, or an alkyl group containing 1 to 8 C atoms; wherein Z³ is: a monofunctional aromatic or cycloaliphatic or aliphatic group containing 1 to 8 C atoms, which optionally contains at least one carboxylate, nitrile, nitro, phosphonate, or sulfonic or sulfonate group, or a group having a formula of A-Si(Z²)_(3-a)(OZ¹)_(a); wherein Z⁴ is H or a monofunctional aromatic or cycloaliphatic or aliphatic group containing 1 to 8 C atoms; wherein Z⁵ is : a b-functional aromatic or araliphatic or cycloaliphatic or aliphatic group containing 1 to 40 C atoms, or a group having a formula of A-Si(Z²)_(3-a)(OZ¹)_(a); wherein X is O or S; wherein a is 1 or 2 or 3; and wherein b is 1 or 2 or 3 or 4; with the proviso that either Z³ or Z⁴ is H.
 2. The silane of claim 1, wherein A is a propylene group.
 3. The silane of claim 1, wherein b is not 1, and Z⁴ is H.
 4. The silane of claim 1, wherein b is
 1. 5. The silane of claim 1, wherein the silane of formula (I) contains no aromatic substituents.
 6. A substrate having a surface that is coated or derivatized with a silane of formula (I)

wherein A is an optionally branched alkylene group containing 1 to 4 C atoms, or a phenylene group; wherein Z¹ is H or an alkyl group containing 1 to 4 C atoms; wherein Z² is H, a phenyl group, or an alkyl group containing 1 to 8 C atoms; wherein Z³ is: H, a monofunctional aromatic or cycloaliphatic or aliphatic group containing 1 to 8 C atoms, which optionally contains at least one carboxylate, nitrile, nitro, phosphonate, or sulfonic or sulfonate group, or a group having a formula of A-Si(Z²)_(3-a)(OZ¹)_(a); wherein Z⁴ is H or a monofunctional aromatic or cycloaliphatic or aliphatic group containing 1 to 8 C atoms; wherein Z⁵ is: a b-functional aromatic or araliphatic or cycloaliphatic or aliphatic group containing 1 to 40 C atoms, or a group having a formula of A-Si(Z²)_(3-a)(OZ¹)_(a); wherein X is O or S; wherein a is 1 or 2 or 3; and wherein b is 1 or 2 or 3 or 4; with the proviso that either Z³ or Z⁴ is H.
 7. The substrate of claim 6, wherein the substrate is an inorganic filler containing at least one metal atom selected from the group consisting of atoms, Si atoms, Al atoms, and mixtures thereof.
 8. The substrate of claim 7, wherein an average particle size of the inorganic filler is less than 50 microns.
 9. A silane of formula (I a)

wherein A is —CH₂—CH₂—CH₂—, Z¹ is CH₃, Z³ is H, Z⁴ is CH₃, Z⁵ is CH₃, X is O, and b is 1; or A is —CH₂—CH₂—CH₂—, Z¹ is CH₃, Z³ is CH₃, Z⁴ is H, Z⁵ is CH₃, X is O, and b is 1; or A is —CH₂—, Z¹ is CH₃ or CH₂CH₃, Z³ is H, Z⁴ is a monofunctional aliphatic group containing 1 to 12 atoms, Z⁵ is a monofunctional aliphatic group containing 1 to 12 C atoms, X is O, and b is
 1. 10. A thermosetting epoxy resin composition comprising: at least one epoxy resin EH having, on average, more than one epoxide group per molecule; an inorganic filler containing at least one metal atom selected from the group consisting of Ca atoms, Si atoms, Al atoms, and mixtures thereof; and at least one silane of formula (I);

wherein A is an optionally branched alkylene group containing 1 to 4 C atoms, or a phenylene group; wherein Z¹ is H or an alkyl group containing 1 to 4 C atoms; wherein Z² is H, a phenyl group, or an alkyl group containing 1 to 8 C atoms; wherein Z³ is: H, a monofunctional aromatic or cycloaliphatic or aliphatic group containing 1 to 8 C atoms, which optionally contains at least one carboxylate, nitrile, nitro, phosphonate, or sulfonic or sulfonate group, or a group having a formula of A-Si(Z²)_(3-a)(OZ¹)_(a); wherein Z⁴ is H or a monofunctional aromatic or cycloaliphatic or aliphatic group containing 1 to 8 C atoms; wherein Z⁵ is: a b-functional aromatic or araliphatic or cycloaliphatic or aliphatic group containing 1 to 40 C atoms, or a group having a formula of A-Si(Z²)_(3-a)(OZ¹)_(a); wherein Z is O or S; wherein a is 1 or 2 or 3; and wherein b is 1 or 2 or 3 or 4; with the proviso that either Z³ or Z⁴ is H.
 11. The thermosetting epoxy resin composition of claim 10, wherein silane of formula (I) present in the thermosetting epoxy resin composition in amount of from 0.001-20% by weight, relative to the weight of the thermosetting epoxy resin composition.
 12. The thermosetting epoxy resin composition of claim 10, further comprising at least one heat-activatable curing agent B selected from the group consisting of dicyandiamide, guanamine, guanidine, aminoguanidine a substituted urea, phenyldimethyl urea, imidazoles, imidazole salts, imidazolines, amine complexes and derivatives thereof.
 13. The thermosetting epoxy resin composition of claim 10, wherein the thermosetting epoxy resin composition further comprises at least one impact modifier D.
 14. The thermosetting epoxy resin composition of claim 13, wherein the impact modifier D is selected from the group consisting of blocked polyurethane polymers, liquid rubbers, epoxy resin-modified liquid rubbers, block copolymers, and core-shell polymers.
 15. The thermosetting epoxy resin composition of claim 14, wherein the impact modifier D is a blocked polyurethane polymer of formula (IV)

wherein: Y¹ is a linear or branched polyurethane polymer PU1, terminated by m+m′ isocyanate groups, after removal of all end-position isocyanate groups; Y² is independently a blocking group that cleaves at a temperature above 100° C.; Y³ is independently a group of formula (IV′)

wherein R⁴ is a radical of an aliphatic, cycloaliphatic, aromatic, or araliphatic epoxy, containing a primary or secondary hydroxyl group, after removal of the hydroxide and epoxy groups; wherein p is b 1, 2, or 3, and wherein m and m′ each stand for an integer between 0 and 8, with the proviso that a value of m+m′ is from 1 to
 8. 16. A method for the adhesive bonding of heat-stable substrates, the method comprising: i) applying the thermosetting epoxy resin composition of claim 10 to a surface of a first heat-stable substrate S1; ii) contacting the applied thermosetting epoxy resin composition with the surface of second heat-stable substrate S2; iii) heating the contacted thermosetting epoxy resin composition to a temperature of 100-220° C.; wherein substrate S2 is composed of a material that is identical to or different from substrate S1.
 17. A cured epoxy resin composition obtained by heating the thermosetting epoxy resin composition claim
 10. 